Proposal (563) to South American Classification Committee

Recognize the genus Rhopias for Myrmotherula gularis

Effect on SACC: This would transfer Myrmotherula gularis from its current placement in Myrmotherula to the monotypic genus Rhopias.

Background: SACC currently recognizes 25 species in the genus Myrmotherula, but even early authors considered the plumage-based taxonomy of the genus problematic (i.e., Cory & Hellmayr, 1924; Peters, 1951). Subsequent studies based on morphological, vocal, and phylogenetics analyses showed that Myrmotherula as currently recognized is polyphyletic (Hackett & Rosenberg, 1990; Gonzaga, 2001; Irestedt, et al., 2004; Brumfield et al., 2007; Bravo et al. 2012). Specifically, two of these studies showed that Myrmotherula gularis was only distantly related to other Myrmotherula (Gonzaga, 2001; Bravo et al., 2012), but no formal proposition to remove the species from this genus was made.

New Information: Results from a subset of taxa from a densely sampled molecular phylogeny (218 of 224 species) of the Thamnophilidae, with a more inclusive sampling of M. gularis, and data from syrinx morphology confirmed that the species is not related to other Myrmotherula (Tribe Formicivorini), and that it belongs in the tribe Thamnophilini (Belmonte-Lopes et al., 2012).  However, lack of resolution at the base of the Thamnophilini impeded certainty about the close relatives of M. gularis. With low support, it was recovered by different analyses as a long branch that is sister to a clade that includes the large antshrikes (Cymbilaimus, Taraba, Hypoedaleus, Batara, Mackenziaena, and Frederickena) or to Dichrozona (Bravo et al., 2012; Belmonte-Lopes et al., 2012). Analyses of the condition of the Musculus vocalis ventralis also support the placement of M. gularis outside Myrmotherula; M. gularis showed a character state also found in the large antshrikes, but that is absent in Myrmotherula and Dichrozona (Belmonte-Lopes et al., 2012).

Because of the morphological and ecological distinctiveness of M. gularis with respect to all other genera in the Thamnophilini, merging M. gularis into any other genus would create an excessively heterogeneous taxon. Therefore, it was proposed that M. gularis be placed in a monotypic genus, for which the name Rhopias Cabanis and Heine, 1859-1860 is available (Belmonte-Lopes et al., 2012).

Recommendation: We recommend a YES vote to the recognition of Rhopias as a monotypic genus for “Myrmotherula” gularis.

References:

BELMONTE-LOPES, R.; BRAVO, G.A.; BORNSCHEIN, M.R.; MAURÍCIO, G.N.; PIE, M.R. & BRUMFIELD, R.T. 2012. Genetic and morphological data support placement of Myrmotherula gularis (Spix) in the monotypic genus Rhopias Cabanis and Heine (Aves: Passeriformes: Thamnophilidae). Zootaxa 3451: 1-16.

GONZAGA, L.A.P. 2001. Análise filogenética do gênero Formicivora Swainson, 1825 (Aves: Passeriformes: Thamnophilidae) baseada em caracteres morfológicos e vocais. PhD. Dissertation. Universidade Federal do Rio de Janeiro, Rio de Janeiro, 215 pp.

[Other references in SACC literature]

Ricardo Belmonte-Lopes, Gustavo A. Bravo & Marcos R. Bornschein, November 2012.

Note from Remsen: Rhopias tentatively placed in linear sequence to follow Thamnophilus and to precede Megastictus to be consistent with its placement in the tree of Belmonte-Lopes et al. (2012).

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Comments from Stiles: “YES - no other solution appears reasonable.”

Comments from Remsen: “YES.  The new data require resurrection of Rhopias.”

Comments from Nores: “YES. Molecular analysis and data from syrinx morphology show clearly that Myrmotherula gularis is not related to other Myrmotherula or Epinecrophylla (Tribe Formicivorini). For this reason, the resurrection of Rhopias appears very reasonable.”

Comments from Stotz: “YES. Myrmotherula gularis has always seemed an outlier in Myrmotherula, and doesn’t fit well with anything else.”

Comments from Pacheco: “YES.  The results of the analysis of Belmonte-Lopes et al. are consistent with adoption of this monotypic Rhopias.”

Comments from Zimmer: “YES.  I think that placement in a monotypic genus is by far the best approach, given the molecular data and the data regarding syrinx morphology.  This one has presented a vexing problem for some time.  The black-and-white checkered throat suggested a close relationship with the stipple-throated, dead-leaf foraging Epinecrophylla, but nest architecture and foraging ecology suggested, and molecular data confirm, otherwise.  Some similarities in behavior, nest architecture and vocalizations suggested a relationship with guttata and hauxwelli (now treated in the genus Isleria). With the molecular and syringeal data rejecting any previously proposed close relationships, and suggesting that gularis is sister to the clade containing the big antshrikes (bizarre in my opinion) or to Dichrozona (closer, but still a huge morphological and behavioral stretch), erecting a monotypic genus for gularis seems to be not only the most reasonable, but also the only palatable option, and the name Rhopiasis available.”

Comments from Pérez-Emán: “YES. Belmonte-Lopes et al. (2012) presented a strong case showing how distinctive is this taxon in relation to other Thamnophilidae, leaving recognition of a monotypic genus as the best taxonomic solution.”